after uploading some pictures, I linked them to a portfolio item. When I insert the gallery in the post, it shows for example 30 picts but after updating there are always 7 more blank thumbs without linking (total 37 picts). Even if I insert only one it adds seven more. How do I get rid of this? Any ideas?

Sounds like a WP bug to be honest. We just use the standard gallery function and the rss widget is provided by wp too. I think that’s something we can’t solve on the theme level but which is a core problem/bug. I can only recommend using nextgen gallery – it’ offers more features and is more flexible nevertheless.